The overall goal of this project is to develop novel therapeutic agents against Yersinia pestis, the causative agent of plague and one of the most dangerous potential bioweapons. In this exploratory project, we will develop novel approaches to obtain previously inaccessible secondary metabolites from actinomycetes. These organisms have traditionally served as the main source for antibiotics. Recent whole genome sequencing of two well-studied streptomycete species revealed potential additional modules for synthesis of antibiotics. This agrees well with previous data from the literature indicating that the majority of antibiotics are not expressed under in vitro growth conditions. It is reasonable to assume that antibiotics are expressed in a natural environment, where they provide a competitive advantage to the producing organism. Our overall approach is to emulate the natural environment to elicit production of antibiotics. We will develop two elicitation methods in this project. According to our preliminary data, there is a particular type of compounds that emulate a critical aspect of the environment and act as antibiotic elicitors. A detailed examination of the ability of these substances to elicit production of previously unknown antibiotics will be performed with a panel of known actinomycetes. Another method of antibiotic elicitation will be based on culturing microorganisms in their natural environment, soil, in a diffusion chamber that we have previously used to grow "unculturable" microorganisms (Kaeberlein, T., Lewis, K., and Epstein, S.S. (2002) Science 296:1127-1129). Finding new compounds with antimicrobial activity from known organisms using elicitation will constitute proof of principle for the proposed approach. The methods we develop will allow for large-scale screening and validation in Phase II which will lead to the development of a new anti-Y. pestis therapy.